- HTTP/1 is "1 HTTP stream over 1 TCP-ish L4 connection" (TLS-over-TCP is a TCP-ish L4 connection)
- HTTP/2 is "multiple HTTP streams multiplexed over 1 TCP-ish L4 connection"
- HTTP/3 is "HTTP over QUIC"
HTTP/3 is meant to replace HTTP/1 or HTTP/2 only to the degree that QUIC replaces TCP. In your air-gapped system, or for local development, QUIC-instead-of-TCP is less compelling.
- HTTP/2 is "multiple HTTP streams multiplexed over 1 TCP-ish L4 connection"
- HTTP/3 is "HTTP over QUIC"
HTTP/3 is meant to replace HTTP/1 or HTTP/2 only to the degree that QUIC replaces TCP. In your air-gapped system, or for local development, QUIC-instead-of-TCP is less compelling.